Heat stress and thermal dehydration: Lactacidemia and plasma volume regulation

Y. Zurovski, L. Eckstein, M. Horowitz*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

This investigation was undertaken to study heat stress and dehydration effects on 1) plasma lactic acid (LA) concentration and 2) plasma LA effect on plasma volume conservation during thermal dehydration. Experiments were performed on conscious nonacclimated and heat-acclimated laboratory rats subjected to various levels of heat stress and/or dehydration (37-42°C with and without drinking water). During the exposures, rectal temperature (T(re)), plasma LA pyruvic acids, and hematocrit were measured. From these data, excess LA, indicative of anaerobic metabolism, was calculated. In separate experiments, transvascular protein efflux (half time of Evans blue- labeled albumin) was measured before and after plasma LA elevation, either by LA infusion or thermal dehydration. The results show that elevation of plasma LA was associated with a rise in T(re), with accelerated elevation within a T(re) range of 41-42°C. LA concentrations were similar for the same T(re) in all experimental groups. In nonacclimated rats, this rise was accompanied by a significant rise in excess LA. In acclimated rats, only a minor rise in excess LA was observed. A positive correlation was found between plasma LA elevation and the increase in plasma protein efflux. It is concluded that there is a temperature threshold for the rise in plasma LA. In nonacclimated rats, local hypoxia may contribute to this rise. The data also suggest that, in nonacclimated rats, lactacidemia accelerates plasma protein and fluid loss, leading to circulatory failure during acute thermal dehydration.

Original languageEnglish
Pages (from-to)2434-2439
Number of pages6
JournalJournal of Applied Physiology
Volume71
Issue number6
DOIs
StatePublished - 1991

Keywords

  • capillary permeability
  • excess lactic acid
  • heat acclimation
  • lactic acid

Fingerprint

Dive into the research topics of 'Heat stress and thermal dehydration: Lactacidemia and plasma volume regulation'. Together they form a unique fingerprint.

Cite this